The present invention relates to a stone lifting device which is suitable for lifting cobblestones, paving stones and the like from their preset positions in the ground.
Such stone lifting devices are already known. Their purpose in particular is to pull out individual, e.g., damaged or sunken stones from existing cobblestone pavements, which may consist of composite stone, clinker brick, natural stone, and slabs of various shapes, and to replace said stones with corresponding new ones. For parking lots, it is common to initially build the entire cobblestone pavement for economic reasons so as not to interfere with the work progress, and only then, prior to compacting, use stone lifting devices to lift out individual stones and replace them with colored marking stones. Also for setting posts or cornerstones, etc., it is often necessary to remove individual cobblestones from cobblestone pavement.
In particular, the trend to premium cobblestone material with specially treated surfaces often requires replacing damaged stones after sand has been filled in the gaps between the stones and the pavement has been compacted. These stones are solidly anchored to the adjacent stones and it is very difficult to pull them out.
In this regard, stone lifting devices are known that essentially are built in the form of pliers and exhibit two handles, which are pivoted in relation to each other at a common lower center of rotation. One of the handles exhibits a gripping jaw, which can be inserted in the gap adjacent to one side of the cobblestone to be lifted out. Correspondingly, the other handle exhibits a gripping jaw, which can be inserted in the gap adjacent to the opposite side of the cobblestone. Both gripping jaws consist of hardened spring steel and are designed in a knife-like manner such that they can be inserted into the gaps with ease. By moving the handles toward each other, the cobblestone is clamped between the two gripping jaws such that it can be lifted out of the cobblestone pavement through a vertical movement of the stone lifting device.
However, one problem is that for stones that are solidly embedded in the cobblestone pavement working with such a stone lifting device is relatively laborious because during the entire manipulation of a stone, the operating person must exert one force to clamp the cobblestone between the gripping jaws and at the same time exert another force to lift the stone lifting device vertically.
To overcome this difficulty, a self-clamping stone lifting device has been developed and is available commercially from Feltes GmbH, D-40882 Ratingen, Germany, where the handles are connected to each other via a clamping design, which in part applies and maintains the force for moving the gripping parts through its own weight.
However, one problem of this known self-clamping stone lifting device is that its design is relatively complex and complicated and that its handling is cumbersome. Furthermore, modifying the clamping force is cumbersome requiring the adjustment of setscrews and the like.